Outage Analysis of Flexible Overlay Communications

Overlay communications asks secondary transmitters (STs) to aid primary transmitters (PTs) for rewarding the usage of primary spectrum for transmission, dramatically meliorating spectral efficiency. Our work proposes a flexible overlay communications wherein STs operate adaptively with amongst direct transmission, decode-and-forward, and amplify-and-forward to further ameliorate spectral efficiency, system performance, and energy efficiency. The outage probability of the flexible overlay communications is analyzed and evaluated through which the efficacy of this communications is corroborated.